c++primer第五版第十七章练习
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2022-07-04 11:55:39
17.1、17.2
#include
#include
#include
#include
int main()
{
using namespace std;...
17.1、17.2
#include
#include
#include
#include
int main()
{
using namespace std;
tuple ti{ 10,20,30 };
cout << get<0>(ti) << " " << get<1>(ti) << " " << get<2>(ti) << endl;
tuple, pair> top;
system("pause");
return 0;
}
17.3
#pragma once
#include
#include
#include
#include
#include
#include
#include
class textquery
{
public:
typedef std::vector::size_type _type;
typedef std::tuple>, std::shared_ptr>> queryresult;
private:
std::shared_ptr> file;
std::map>> ms;
public:
textquery(std::ifstream &ifile);
queryresult query(const std::string &s)const;
queryresult query_tuple(const std::string &s);
};
#include "textquery.h"
#include
#include
#include
textquery::textquery(std::ifstream &ifile) :file(new std::vector)
{
std::string line;
while (std::getline(ifile, line))
{
file->push_back(line);
std::stringstream sstr(line);
std::string word;
while (sstr >> word)
{
//std::shared_ptr> &sptr = ms[word];
auto &sptr = ms[word];
if (!sptr)
sptr.reset(new std::set<_type>);
sptr->insert(file->size() - 1);
}
}
}
textquery::queryresult textquery::query(const std::string &s)const
{
static std::shared_ptr> nodata(new std::set<_type>);
auto iter = ms.find(s);
if (iter == ms.end())
return queryresult(s, nodata, file);
else
return queryresult(s, iter->second, file);
}
textquery::queryresult textquery::query_tuple(const std::string &s)
{
static std::shared_ptr> nodata(new std::set<_type>);
auto iter = ms.find(s);
if (iter == ms.end())
return queryresult(s, nodata, file);
else
return queryresult(s, iter->second, file);
}
#include
#include
#include "textquery.h"
std::ostream &operator<<(std::ostream &os, const textquery::queryresult &q)
{
os << std::get<0>(q) << "\n";
for (auto &x : *std::get<1>(q))
os << x << " ";
os << "\n";
for (auto &x : *std::get<2>(q))
os << x << " ";
return os;
}
int main(int agrc,char **argv)
{
using namespace std;
ifstream ifile(argv[1]);
if (!ifile)
{
cout << "open file error!";
exit(1);
}
textquery b(ifile);
cout<
原来的方法比较好
tuple用于快速生成，但却难以重构，可用于快速的测试
17.4、17.5、17.6
#pragma once
#include
#include
class sales_data
{
friend sales_data operator+(const sales_data& lhs, const sales_data& rhs);
friend std::ostream &operator << (std::ostream& os, const sales_data& s);
friend std::istream &operator >> (std::istream& is, sales_data& s);
friend sales_data add(const sales_data&, const sales_data&);
friend std::ostream &print(std::ostream&, const sales_data&);
friend std::istream &read(std::istream&, sales_data&);
public:
sales_data() = default;
sales_data(const std::string &s) : bookno(s) { }
sales_data(const std::string &s, unsigned n, double p) :bookno(s), units_sold(n), revenue(p*n){}
sales_data(const sales_data &s) :bookno(s.bookno), units_sold(s.units_sold), revenue(s.revenue){}
sales_data(sales_data&& s) :bookno(s.bookno), units_sold(s.units_sold), revenue(s.revenue){}
~sales_data() {}
sales_data(std::istream &);
std::string isbn() const { return bookno; }
sales_data& combine(const sales_data&);
sales_data& operator =(const sales_data& rhs);
sales_data& operator =(const std::string& rhs);
sales_data& operator +=(const sales_data& rhs);
explicit operator std::string() const { return bookno; }
explicit operator double() const { return revenue; }
double avg_price() const;
private:
std::string bookno;
unsigned units_sold = 0;
double revenue = 0.0;
};
inline sales_data operator+(const sales_data& lhs, const sales_data& rhs)
{
sales_data sum = lhs;
sum += rhs;
return sum;
}
std::ostream &operator << (std::ostream& os, const sales_data& item);
std::istream &operator >> (std::istream& is, sales_data& s);
sales_data add(const sales_data&, const sales_data&);
std::ostream &print(std::ostream&, const sales_data&);
std::istream &read(std::istream&, sales_data&);
#include
#include "sales_data.h"
using std::istream; using std::ostream;
sales_data::sales_data(std::istream &is)
{
read(is, *this);
}
double sales_data::avg_price() const {
if (units_sold)
return revenue / units_sold;
else
return 0;
}
sales_data &sales_data::combine(const sales_data &rhs)
{
units_sold += rhs.units_sold;
revenue += rhs.revenue;
return *this;
}
sales_data &sales_data::operator =(const sales_data &rhs)
{
this->bookno = rhs.bookno;
this->revenue = rhs.revenue;
this->units_sold = rhs.units_sold;
return *this;
}
sales_data &sales_data::operator =(const std::string &rhs)
{
*this = sales_data(rhs);
return *this;
}
sales_data &sales_data::operator +=(const sales_data &rhs)
{
this->revenue += rhs.revenue;
this->units_sold += rhs.units_sold;
return *this;
}
sales_data add(const sales_data &lhs, const sales_data &rhs)
{
sales_data sum = lhs;
sum.combine(rhs);
return sum;
}
istream &read(istream &is, sales_data &item)
{
double price = 0;
is >> item.bookno >> item.units_sold >> price;
item.revenue = price * item.units_sold;
return is;
}
ostream &print(ostream &os, const sales_data &item)
{
os << item.isbn() << " " << item.units_sold << " "<< item.revenue << " " << item.avg_price();
return os;
}
std::ostream &operator <<(std::ostream &os, const sales_data &item)
{
os << item.isbn() << " " << item.units_sold << " "<< item.revenue << " " << item.avg_price();
return os;
}
std::istream &operator >>(std::istream &is, sales_data &s)
{
double price;
is >> s.bookno >> s.units_sold >> price;
if (is)
s.revenue = s.units_sold * price;
else
s = sales_data();
return is;
}
#include
#include
#include
#include
#include //equal_range
#include
#include //accumulate
#include
#include "sales_data.h"
typedef std::tuple::size_type, std::vector::const_iterator, std::vector::const_iterator> matches;
typedef std::pair::size_type, std::pair::const_iterator, std::vector::const_iterator>>matches_pair;
inline bool compareisbn(const sales_data &ls, const sales_data &rs)
{
return ls.isbn() < rs.isbn();
}
std::vector findbook(const std::vector> &f, const std::string &book)//17.4
{
std::vector ret;
for (auto it = f.cbegin(); it != f.cend(); ++it)
{
auto found = equal_range(it->cbegin(), it->cend(), book, compareisbn);
if (found.first != found.second)
ret.push_back(make_tuple(it - f.cbegin(), found.first, found.second));
}
return ret;
}
std::vector findbook_pair(const std::vector> &f, const std::string &book)//17.5
{
std::vector ret;
for (auto it = f.cbegin(); it != f.cend(); ++it)
{
auto found = equal_range(it->cbegin(), it->cend(), book, compareisbn);
if (found.first != found.second)
ret.push_back(make_pair(it - f.cbegin(), make_pair(found.first, found.second)));
}
return ret;
}
struct matches_struct//17.6
{
std::vector::size_type st;
std::vector::const_iterator first;
std::vector::const_iterator second;
matches_struct(std::vector::size_type s, std::vector::const_iterator fi, std::vector::const_iterator se) :st(s), first(fi), second(se) {}
};
std::vector findbook_struct(const std::vector> &f, const std::string &book)
{
std::vector ret;
for (auto it = f.cbegin(); it != f.cend(); ++it)
{
auto found = equal_range(it->cbegin(), it->cend(), book, compareisbn);
if (found.first != found.second)
ret.push_back(matches_struct(it - f.cbegin(), found.first, found.second));
}
return ret;
}
void reportrestults(std::istream &is, std::ostream &os, const std::vector> &f)
{
std::string s;
while (is >> s)
{
auto tran = findbook(f, s);
if (tran.empty())
{
std::cout << s << " not found in any stores" << std::endl;
continue;
}
for (const auto &x : tran)
os << "store " << std::get<0>(x) << " sales: " << std::accumulate(std::get<1>(x), std::get<2>(x), sales_data(s)) << std::endl;
}
}
std::vector *write_sales(std::fstream &f)
{
sales_data temp;
auto ptr = new std::vector;
while (read(f, temp))
{
ptr->push_back(temp);
}
return ptr;
}
int main(int argc,char **argv)
{
using namespace std;
fstream f1(argv[1]), f2(argv[2]), f3(argv[3]);
if (!f1&&!f2&&!f3)
{
cerr << "error!";
exit(1);
}
std::vector> file;
file.push_back(*write_sales(f1));
file.push_back(*write_sales(f2));
file.push_back(*write_sales(f3));
reportrestults(cin, cout, file);
system("pause");
return 0;
}
17.7
更倾向于tuple，相对于其他版本，它更方便
17.8
创建的是使用sales_data默认构造函数创建的对象
这样的结果就是书名为空，其他数据为0
17.9
a、00000000 00000000 00000000 00000000 00000000 00000000 00000000 00100000
b、00000000 00001111 01101001 10110101
c、视输入的内容而定，但是输入的字符非0或1那么就会抛出invalid_argument异常
17.10
#include
#include
int main()
{
using namespace std;
int v[] = { 1,2,3,5,8,13,31 };
bitset<32> bit1;
for (auto x : v)
bit1.set(x);
bitset<32> bit2;
for (size_t i = 0; i < bit1.size(); ++i)
bit2[i] = bit1[i];
cout << bit1 << endl << bit2;
system("pause");
return 0;
}
17.11、17.12、17.13
#pragma once
#include
#include
#include
template
class bit //17.11
{
std::bitset bit;
public:
bit() = default;
bit(std::string &s) :bit(s) {}
void updata(size_t n, bool b) //17.12
{
bit.set(n, b);
}
template //17.13
friend size_t text(const bit &lb, const bit &rb);
template
friend std::ostream &operator<<(std::ostream &os, const bit &b);
};
template
size_t text(const bit &lb, const bit &rb)
{
auto temp = lb.bit^rb.bit; //得出答错的题目
temp.flip(); //翻转所有
return temp.count(); //返回答对的题目
}
template
std::ostream &operator<<(std::ostream &os, const bit &b)
{
os << b.bit;
return os;
}
17.14
#include
#include
#include
int main()
{
using namespace std;
try {
regex reg("[^cei");
}
catch (regex_error e){
cout << e.what() << "\ncode: " << e.code() << endl;
}
system("pause");
return 0;
}
17.15、17.16
#include
#include
#include
int main()
{
using namespace std;
regex reg("[[:alpha:]]*[^c]ei[[:alpha:]]*",regex::icase);//17.15
string str;
smatch m;
while (cin >> str&&str!="q")
{
if (regex_search(str, m, reg))
cout << str << " is ok" << endl;
else
cout << str << " is not ok" << endl;
}
reg = "[^c]ei";//17.16 好像...并没有什么变化
while (cin >> str&&str != "q")
{
if (regex_search(str, m, reg))
cout << str << " is ok" << endl;
else
cout << str << " not is ok" << endl;
}
system("pause");
return 0;
}
17.17、17.18
#include
#include
#include
#include
#include
int main(int argc, char **argv)
{
using namespace std;
ifstream file(argv[1]);
if (!file)
{
cerr << "open file error!";
exit(1);
}
string p("[^c]ei");
p = "[[:alpha:]]*" + p + "[[:alpha:]]*";
regex reg(p, regex::icase);
string temp, str;
while (getline(file, temp))
str = str + temp + "\n";
vector vec{ "albeit","beige","feint","heir","reign","their",
"counterfeit","foreign","inveigh","rein","veil","deign",
"forfeit","inveigle","seize","veineiderdown","freight",
"leisure","skein","weigheight","heifer","neigh","sleigh",
"weighteither","height","neighbour","sleight","weirfeign",
"heinous neither surfeit weird" };
for (sregex_iterator it(str.begin(), str.end(), reg), end_it; it != end_it; ++it)
{
if (find(vec.begin(), vec.end(), it->str()) != vec.end())//17.8
continue;
cout << it->str();
system("pause");
auto pos = it->prefix().length();
cout << it->prefix().str().substr(pos > 40 ? pos - 40 : 0) << "[> " << it->str() << "<]" << it->suffix().str().substr(0, 40) << endl;
}
system("pause");
return 0;
}
17.19
m4和m6都是分隔符，两者必须是相同的字符，如果一方不匹配或两者不相同，那么就为true
17.20
#include
#include
#include
bool valid(const std::smatch &m);
int main()
{
using namespace std;
string phone = "(\\()?(\\d{3})(\\))?([-. ])?(\\d{3})([-. ])?(\\d{4})";
regex reg;
try {
reg.assign(phone);
}
catch (regex_error e) {
cout << e.what() << "\ncode: " << e.code();
}
smatch m;
string s;
while (getline(cin, s)&&s!="q")
{
for (sregex_iterator it(s.begin(), s.end(), reg), end_it; it != end_it; ++it)
{
if (valid(*it))
cout << "valid: " << it->str() << endl;
else
cout << "not valid: " << it->str() << endl;
}
}
system("pause");
return 0;
}
bool valid(const std::smatch &m)
{
if (m[1].matched)//如果存在"("左括号
// ")"右括号必须存在，和区号分隔符不存在，或区号分隔符为空格
return m[3].matched && (m[4].matched == 0 || m[4].str() == " ");
else //如果不存在"("左括号
// ")"右括号必须不存在，和区号分隔符与号码分隔符必须相同
return !m[3].matched&&m[4].str() == m[6].str();
}
17.21
#include
#include
#include
#include
#include
#include
struct personinfo {
std::string name;
std::vector phones;
};
bool valid(const std::smatch &m);
bool read_record(std::istream &is, std::vector &people);
void format_record(std::ostream &os, const std::vector &people);
int main()
{
using namespace std;
vector people;
string filename;
cout << "enter input file name:";
cin >> filename;
ifstream fin(filename);
if (read_record(fin, people))
{
cout << "enter output file name:";
string outname;
cin >> outname;
ofstream fout(outname, ofstream::trunc); //覆盖文件:trunc
format_record(fout, people);
}
else
cout << "open file error:" << filename << endl;
system("pause");
return 0;
}
bool valid(const std::smatch &m)
{
if (m[1].matched)
return m[3].matched && (m[4].matched == 0 || m[4] == " ");
else
return !m[3].matched&&m[4].str() == m[6].str();
}
bool read_record(std::istream &is, std::vector &people)
{
if (is)
{
std::string line, word;
while (getline(is, line)) //读取一行到line
{
personinfo info;
std::istringstream record(line); //关联流到line，把record绑定到要读取的行line
record >> info.name; //把流中第一个字符串输入到name，这一行的第一个，也就是名字
while (record >> word)
info.phones.push_back(word);//把名字后面的电话号码保存
people.push_back(info); //添加一个联系人
}
return true;
}
else
return false;
}
void format_record(std::ostream &os, const std::vector &people)
{
std::string phone = "(\\()?(\\d{3})(\\))?([-. ])?(\\d{3})([-. ]?)(\\d{4})";
std::regex reg;
try {
reg.assign(phone);
}
catch (std::regex_error e)
{
std::cout << e.what() << "\ncode: " << e.code() << std::endl;
}
std::smatch m;
for (const auto &x : people)
{
std::ostringstream formatted, badnums;
for (const auto &n : x.phones)
{
for (std::sregex_iterator it(n.begin(), n.end(), reg), end_it; it != end_it; ++it)
{
if (!valid(*it))
badnums << " " << n; //将数据放入流，暂时保存
else
formatted << " " << n;
}
}
if (badnums.str().empty())
os << x.name << " " << formatted.str() << std::endl; //将流中的数据以string的形式放入os流中
else
std::cerr << "file error: " << x.name << " invalid number " << badnums.str() << std::endl;
}
}
17.22
#include
#include
#include
bool valid(const std::smatch &m);
int main()
{
using namespace std;
string phone = "(\\()?(\\d{3})(\\))?([[:blank:]]*)?(\\d{3})([[:blank:]]*)?(\\d{4})"; //（[[:blank:]]）匹配0-哪个空格或制表符
regex reg;
try {
reg.assign(phone);
}
catch (regex_error e) {
cout << e.what() << "\ncode: " << e.code();
}
smatch m;
string s;
while (getline(cin, s)&&s!="q")
{
for (sregex_iterator it(s.begin(), s.end(), reg), end_it; it != end_it; ++it)
{
if (valid(*it))
cout << "valid: " << it->str() << endl;
else
cout << "not valid: " << it->str() << endl;
}
}
system("pause");
return 0;
}
bool valid(const std::smatch &m)
{
if (m[1].matched)//如果存在"("左括号
// ")"右括号必须存在，和区号分隔符不存在，或区号分隔符为空格
return m[3].matched && (m[4].matched == 0 || m[4].str() == " ");
else //如果不存在"("左括号
// ")"右括号必须不存在，和区号分隔符与号码分隔符必须相同
return !m[3].matched&&m[4].str() == m[6].str();
}
17.23
#include
#include
#include
int main()
{
using namespace std;
string s = "(\\d{5})([-])?(\\d{4})?";
string num;
regex reg(s);
smatch m;
while (getline(cin, num) && num != "q")
{
for (sregex_iterator it(num.begin(), num.end(), reg), end_it; it != end_it; ++it)
{
if ((*it)[3].matched)
cout << it->str();
else
cout << it->str(1);
cout << endl;
}
}
system("pause");
return 0;
}
17.24
#include
#include
#include
int main()
{
using namespace std;
string phone = "(\\()?(\\d{3})(\\))?([[:blank:]]*)?(\\d{3})([[:blank:]]*)?(\\d{4})";
regex reg;
try {
reg.assign(phone);
}
catch (regex_error e) {
cout << e.what() << "\ncode: " << e.code();
}
string fmt = "$2.$5.$7";
smatch m;
string s;
while (getline(cin, s) && s != "q")
{
cout << regex_replace(s, reg, fmt) << endl;
}
system("pause");
return 0;
}
17.25
#include
#include
#include
int main()
{
using namespace std;
string pattern = "(\\()?(\\d{3})(\\))?([-. ])?(\\d{3})([-. ])?(\\d{4})";
string fmt = "$2.$5.$7";
regex r(pattern);
string s;
while (getline(cin, s))
{
smatch result;
regex_search(s, result, r);
if (!result.empty())
{ //prefix输出匹配前的字符 //format(fmt)输出匹配的格式的字符串
cout << result.prefix() << result.format(fmt) << endl;
}
else
{
cout << "木有匹配的" << endl;
}
}
system("pause");
return 0;
}
17.26
#include
#include
#include
int main()
{
using namespace std;
string pattern = "(\\()?(\\d{3})(\\))?([-. ])?(\\d{3})([-. ])?(\\d{4})";
string fmt = "$2.$5.$7";
regex r(pattern);
string s;
while (getline(cin, s))
{
smatch result;
regex_search(s, result, r);
if (!result.empty())
{ //prefix输出匹配前的字符 //suffix输出匹配的字符串后面的字符
cout << result.prefix() << result.suffix()<< endl;
}
else
{
cout << "木有匹配的" << endl;
}
}
system("pause");
return 0;
}
17.27
#include
#include
#include
int main()
{
using namespace std;
string p = "(\\d{5})(\\d{4})";
regex reg(p);
string fmt = "$1-$2";
smatch m;
string n;
while (getline(cin, n) && n != "q")
{
cout << regex_replace(n, reg, fmt, regex_constants::match_flag_type::format_no_copy);
}
system("pause");
return 0;
}
17.28、17.29、17.30
#include
#include
#include
unsigned ran() //17.28
{
std::default_random_engine e;
std::uniform_int_distribution u;
return u(e);
}
unsigned ran(unsigned s)//7.29
{
std::default_random_engine e(s);
std::uniform_int_distribution u;
return u(e);
}
unsigned ran(unsigned s, int f, int l)//17.30
{
std::default_random_engine e(s);
std::uniform_int_distribution u(f, l);
return u(e);
}
int main()
{
using namespace std;
unsigned f, l;
cout << ran() << endl;
cout << ran(time(0));
cout << "enrer seed:";
cin >> f >> l;
cout << ran(time(0), f, l);
system("pause");
return 0;
}
17.31
结果每次都相同。
因为引擎返回相同的随机数序列，所以必须在循环外声明引擎对象，否则每次循环都会创建一个新的引擎（随机数序列不变），而每次都会输出引擎的序列
17.32
resp不在作用域，找不到resp对象
如果在循环里创建resp：
do{
string resp;
}while(...);
在这里，while的前面循环体已经退出，释放所有在循环体定义的对象，所以resp已经不存在
17.33
#include
#include
#include
#include
#include
#include
std::map buildmap(std::ifstream &ifile) //初始化map
{
std::map temp;
std::string str, f, s;
while (getline(ifile, str))
{
std::istringstream sst(str);
sst >> f >> s;
temp[f] = s; //把暗文对应的明文设置
}
return temp;
}
std::string trans(const std::string &s, std::map &m)//转换
{
auto temp = m.find(s);
if (temp != m.end()) //如果是暗文
return m[s]; //返回暗文对应的明文
else
return s;
}
std::string trans_random(const std::string &s, std::map &m)//转换
{
auto temp = m.find(s);
if (temp != m.end()) //如果是暗文
return (m[s]+"!"); //返回暗文对应的明文
else
return s;
}
int main(int argc, char **argv)
{
using namespace std;
ifstream ifpw(argv[1]), iftxt(argv[2]);
if (!ifpw&&!iftxt)
{
cerr << "open file error!\n";
exit(1);
}
map pw(buildmap(ifpw)); //初始化密码文件
string temp, f;
default_random_engine e;
bernoulli_distribution b;
bool t;
while (getline(iftxt, temp))
{
istringstream iss(temp);
while (iss >> f)
{
t = b(e);
if(t)
cout << trans_random(f, pw) << " "; //输出f的明文（如果f是暗文）
else
cout << trans(f, pw) << " "; //输出f的明文（如果f是暗文）
}
cout << endl;
}
system("pause");
return 0;
}
17.34、17.35、17.36
#include
#include
int main()
{
using namespace std;
cout << unitbuf;//17.34
cout << boolalpha << (5 < 4 ? true : false) << noboolalpha << endl;
cout << showpos << showbase << hex << 1000 << " " << oct << 1000
<< " " << dec << 1000 << noshowbase << noshowpos << endl;
cout << uppercase << 3.14159 << " " << hex << 1000 << dec
<< nouppercase << endl;
cout << setfill('#') << setw(10) << internal << showpos << 1024
<< noshowpos << nounitbuf << ends << endl << flush;
cout << setw(10) << left <="" noskipws;="" while="" (cin="" >>="" ch&&ch="" !="q" )="" cout="" <<="" ch;="" cin="" skipws;="" endl;="" uppercase;="" 17.35="" "default="" format:="" "="" 100="" *="" sqrt(2.0)="" '\n'="" "scientific:="" scientific="" "fixed="" decimal:="" fixed="" "hexidecimal:="" uppercase="" hexfloat="" "use="" defaults:="" defaultfloat="" setfill('="" ');="" 17.36="" left="" setw(20)="" format:"="" setw(25)="" right="" "scientific:"="" decimal:"="" "hexidecimal:"="" defaults:"="" "\n\n";="" system("pause");="" return="" 0;="" }
17.37
#include
#include
int main(int argv, char **argc)
{
using namespace std;
ifstream ifile(argc[1]);
if (!ifile)
{
cout << "open file error!";
exit(1);
}
char ar[100];
do {
ifile.getline(ar, 10);//当行超出10个字符时停止
cout << ar << ' ';
} while (ifile);
ifile.close();
system("pause");
return 0;
}
17.38
#include
#include
int main(int argv, char **argc)
{
using namespace std;
ifstream ifile(argc[1]);
if (!ifile)
{
cout << "open file error!";
exit(1);
}
char ar[100];
do {
ifile.getline(ar, 100,' ');
cout << ar << ' ';
} while (ifile);
ifile.close();
system("pause");
return 0;
}
17.39
#include
#include
#include
int main(int argc, char **argv)
{
using namespace std;
fstream iofile(argv[1],fstream::ate|fstream::in|fstream::out);//以只读、只写和文件指针跳到文件尾的方式打开
if (!iofile)
{
cerr << "open file error!";
exit(1);
}
auto end_mark = iofile.tellg();//返回当前文件指针的位置
iofile.seekg(0, fstream::beg);//文件指针跳到文件头，偏移0
size_t cnt = 0;
string line;
while (iofile&&iofile.tellg() != end_mark&&getline(iofile,line))//确定当前文件io流可用与文件当前位置不是原文件尾
{
cnt += line.size() + 1;//增加当前行的长度，+1表示换行符也算
auto mark = iofile.tellg();//保存当前文件指针
iofile.seekp(0, fstream::end);//文件指针跳到文件尾
iofile << cnt;//写入长度
if (mark != end_mark)//确定原位置不是原文件尾
iofile << " ";
iofile.seekg(mark);
}
iofile.seekp(0, fstream::end);
iofile << "\n";
iofile.close();
system("pause");
return 0;
}
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